We tried reaching you on a private message asking for the Service Tag number to ascertain the warranty but did not receive a response. Please feel free to reply to the private message whenever you are available.

I would recommend you get a keyboard replacement. Or send it to a shop and ask them to replace it for you. It could be a software issue as well and I hope it’s that for you. I would recommend you download this:

https://www.dell.com/support/home/en-us/drivers/driversdetails?driverid=9ft4r&oscode=wt64a&productcode=alienware-17-area51m-laptop

Also I hope you have a great day and have you listened to Lost prophets - to H*ll we ride?

no it isn' t a software issue because if I use an external keyboard all the buttons work.

Ok but could you please try redownloading the link I posted in my reply to see if that makes even a difference because it says it helps the devices communicate with the bios better. And if it doesn’t then it seems to be a loose connection and maybe a faulty keyboard.

I have tried to download but the problem is still here

I feel bad for you but all I can recommend is if you go to a microcenter or BestBuy near you to install a new keyboard. or you could yourself replace the keyboard with a compatible model or re-seat the cable itself and make sure no dust is blocking it. I hope this helps.